1. Field of the Invention
The present invention relates to a paper holding device used for holding a paper roll of a varying size accommodated in a label printer, more particularly, to a paper holding device for a label printer, which is modified in its construction to allow a paper roll to be easily and quickly mounted thereon and avoid malfunction of component elements thereof.
2. Description of the Related Art
Generally, a label printer is used to print a trade name, a price, an expiration date, etc. on a label sheet and thereby allow the printed label sheet to be affixed to a product. A number of label sheets are peelably attached to paper which is wound in the form of a roll, in a manner such that they are spaced apart one from another by a certain distance. Depending upon a use, the paper has a width of about 1 to 4 inches.
The paper which is wound in the form of a roll is accommodated in a body of the label printer. The paper roll is rotatably supported in its center hole by a holding device. Consequently, the paper can be continuously paid out from the roll as a printing work proceeds. The paper is fed between a printing roller and a printing head which constitute a printing section, by a feeding roller, to allow the label sheets to be properly printed.
Referring to FIG. 1, there is illustrated a conventional label printer. The label printer has a printer body 3 and a cover 1 which is hingedly coupled to a rear end of the printer body 3. A printing head 2 is installed on a lower surface of a distal end of the cover 1. An accommodating section 4 for accommodating paper P wound in the form of a roll is defined in the printer body 3. A paper guide device for guiding both widthwise edges of the paper P is disposed in front of the accommodating section 4. Further, a printing roller 5 is arranged in front of the paper guide device to be brought into contact with the printing head 2. The printing roller 5 functions to support each label sheet attached to the paper P, upon printing. The paper roll P is held in place by a paper holding device.
Referring to FIG. 2, the conventional paper holding device employed in the label printer includes left and right holders 10 and 20, left and right guide links 30 and 40, a bottom panel 60, a pinion gear 70, a pair of tension springs S, and a fastening screw 80. The left and right holders 10 and 20 respectively have circular protrusions 11 and 21 which are formed at upper ends of the left and right holders 10 and 20 to be inserted into both ends of a center hole P1 of the paper roll P thereby to support the paper roll P, grips 12 and 22 which are formed adjacent to lower ends of the left and right holders 10 and 20, and bases 13 and 23 which are formed at the lower ends of the left and right holders 10 and 20. Each of the bases 13 and 23 is integrally formed, at front and rears ends thereof, with a pair of leg portions. Grooves 13a and 23a are defined on lower surfaces of the leg portions of the bases 13 and 23. Two pairs of first locking holes 13b and 23b are defined through the rear leg portion of the left base 13 and the front leg portion of right base 23 in such a way as to extend in a vertical direction and be communicated with the grooves 13a and 23a, respectively. A first threaded hole 23c is defined through the rear leg portion of the right base 23 to extend in the vertical direction. The left and right guide links 30 and 40 respectively have guide projections 31 and 41 to be received in the grooves 13a and 23a of the left and right holders 10 and 20, guide plates 32 and 42 which are integrally secured to lower ends of the guide projections 31 and 41 and formed, on their respective front and rear surfaces, with rack gears 34 and 44, and hook pieces 33 and 43 which are fastened to respective rear and front surfaces of the guide plates 32 and 42. The guide projections 31 and 41 are defined with two pairs of second locking holes 31a and 41a which are respectively aligned with the two pairs of first locking holes 13b and 23b. A pair of locking screws A are driven into the first locking holes 13b and 23b and the second locking holes 31a and 41a to lock the left and right holders 10 and 20 to the left and right guide links 30 and 40, respectively. The bottom panel 60 is defined with a pair of guide slots 61 and 62 for guiding leftward and rightward movement of the left and right guide links 30 and 40, and has a shaft portion 63 which is formed on a lower surface of the bottom panel 60 between the pair of guide slots 61 and 62 to project downward. As can be readily seen from FIG. 2, the bottom panel 60 further has a plurality of second threaded holes 64 which are defined through the bottom panel 60 over the same width as the right guide slot 62 of the bottom panel 60. The bottom panel 60 is secured with respect to a floor of the printer body 3. The pinion gear 70 is rotatably fitted around the shaft portion 63 of the bottom panel 60 to be meshed with the rack gears 34 and 44 of the guide plates 32 and 42 of the left and right guide links 30 and 40. The pair of tension springs S have one ends which are connected to the hook pieces 33 and 43 of the left and right guide links 30 and 40 and the other ends which are connected to the bottom panel 60. The tension springs S apply elastic pulling force to the left and right guide links 30 and 40. The fastening screw 80 is driven into the first threaded hole 23c and one of the plurality of second threaded holes 64 to fix the right holder 20 to the bottom panel 60.
That is to say, the fastening screw 80 functions to fixedly hold the left and right holders 10 and 20 with respect to the bottom panel 60. By this fact, it is possible to primarily guide both widthwise edges of a separate paper sheet (not shown) which has peelably attached thereto label sheets and is manually fed forward from the rear end of the printer body 3, between the left and right holders 10 and 20 which are properly adjusted in spacing.
Hereafter, operation of the conventional paper holding device for a label printer, constructed as mentioned above, will be described.
Referring to FIGS. 2 and 3, when it is necessary to mount the paper roll P which has a width of about 1 to 4 inches depending upon a use, the paper roll P is first accommodated in the accommodating section 4 which is defined in the printer body 3. Next, the grips 12 and 22 of the left and right holders 10 and 20, which are respectively located at both widthwise ends of the accommodating section 4, are grasped by the hands, and then respectively moved away from each other to define a spacing greater than a width of the paper roll P.
The guide projections 31 and 41 of the left and right guide links 30 and 40 are respectively received in the grooves 13a and 23a which are defined on the lower surfaces of the rear leg portion of the left base 13 and the front leg portion of right base 23. Then, by driving the locking screws A into the first locking holes 13b and 23b of the bases 13 and 23 and the second locking holes 31a and 41a of the guide projections 31 and 41, the bases 13 and 23 and the guide projections 31 and 41 are rigidly coupled with each other, respectively. As a consequence, the left and right holders 10 and 20 and the left and right guide links 30 and 40 can be integrally moved along the guide slots 61 and 62 of the bottom panel 60 in a horizontal direction. If the grips 12 and 22 of the left and right holders 10 and 20 are released, the protrusions 11 and 21 of the left and right holders 10 and 20 are respectively inserted into both ends of the center hole P1 of the paper roll P to support the paper roll P.
Due to the fact that the rack gears 34 and 44 of the guide plates 32 and 42 of the left and right guide links 30 and 40, which can be simultaneously actuated by the medium of the respective left and right holders 10 and 20, are meshed with the pinion gear 70 which is rotatably fitted around the shaft portion 63 projectedly formed on the lower surface of the bottom panel 60, a first combination of the left holder 10 and the left guide link 30 and a second combination of the right holder 20 and the right guide link 40 can be simultaneously moved inward or outward, that is, toward or away from each other. The pair of tension springs S which are connected at both ends thereof to the hook pieces 33 and 43 of the left and right guide links 30 and 40 and the bottom panel 60, apply elastic pulling force to the left and right guide links 30 and 40. Therefore, the protrusions 11 and 21 of the left and right holders 10 and 20 are biased by the pair of tension springs S to be inserted into both ends of the center hole P1 of the paper roll P.
In the state wherein the protrusions 11 and 21 of the left and right holders 10 and 20 are spring-biasedly inserted into both ends of the center hole P1 of the paper roll P, each label sheet attached to the paper P can be printed by the printing head 2 while being fed forward by the feeding roller.
In the meanwhile, in the case that, instead of using the roll type paper P, a separate paper sheet is manually fed forward from the rear end of the printer body 3, the left and right holders 10 and 20, which are properly adjusted in spacing therebetween, function to primarily guide both widthwise edges of the separate paper sheet. To this end, as can be readily seen from FIG. 3, the fastening screw 80 is driven into the first threaded hole 23c which is defined through the rear leg portion of the right base 23 of the right holder 20 and one of the plurality of second threaded holes 64 which are defined through the bottom panel 60, whereby the left and right holders 10 and 20 are fixedly held with respect to the bottom panel 60 to stably guide both widthwise edges of the separate paper sheet.
The conventional paper holding device for holding the paper roll P as described above suffers from defects in that, since the left and right holders 10 and 20 are moved toward or away from each other in the horizontal direction through meshing engagement between the rack gears of the guide plates 32 and 42 of the left and right guide links 30 and 40 and the pinion gear 70, a time required for adjusting a spacing between the left and right holders 10 and 20 is relatively lengthened. Also, in order to mount the paper roll P on the left and right holders 10 and 20, it is necessary to unthread the fastening screw 80 from the bottom panel 60 thereby to allow the left and right guide links 30 and 40 rigidly coupled to the left and right holders 10 and 20 to be moved on the pinion gear 70 and a spacing between the left and right holders 10 and 20 to be freely adjusted, and thereby inconvenience is caused.
Further, upon fixing the holder 20 to the bottom panel 60 using the fastening screw 80, the likelihood of the fastening screw 80 to be lost in the printer body 3 is increased. In this regard, since the fastening screw 80 must be held driven to some extent into the first threaded hole 23c of right holder 20 while the separate paper sheet is manually fed forward between the left and right holders 10 and 20, cumbersomeness is provoked.
Moreover, because a driver is necessarily needed to drive or remove the fastening screw 80 into or from the one of the plurality of second threaded holes 64 upon mounting the paper roll P on the left and right holders 10 and 20 or guiding the separate paper sheet between the fixed left and right holders 10 and 20, a paper roll mounting or separate paper sheet guiding procedure cannot but be retarded. Besides, as the fastening screw 80 is driven into or removed from the second threaded hole 64 a multitude of times, threaded portions of the fastening screw 80 and the second threaded hole 64 are apt to be crushed, whereby uneconomy may result in.
Furthermore, since the left and right guide links 30 and 40 must be repeatedly moved outward or inward, that is, toward or away from each other, with the rack gears 34 and 44 of the guide plates 32 and 42 meshed with the pinion gear 70, to adjust a spacing between the left and right holders 10 and 20, the rack gears and the pinion gear 70 are likely to be broken down. In addition, as the rack gears 34 and 44 and the pinion gear 70 are injection-molded, manufacturing costs cannot but be increased due to design and fabrication of respective molds.
Accordingly, the present invention has been made in an effort to solve the problems occurring in the related art, and an object of the present invention is to provide a paper holding device used for holding a paper roll of a varying size accommodated in a label printer, which is modified in its construction to allow the paper roll to be easily and quickly mounted thereon and left and right holders to be easily and guickly fixed to or freed from a bottom panel upon primarily guiding both widthwise edges of a manually fed separate paper sheet.
In order to achieve the above object, according to one aspect of the present invention, there is provided a paper holding device for a label printer, comprising: left and right holders for supporting both ends, respectively, of a paper roll; left and right guide links respectively locked to lower ends of the left and right holders; a rotation link for operatively connecting the left and right guide links with each other and moving them in leftward and rightward directions; a bottom panel secured with respect to a floor of a printer body, for rotatably installing thereon the rotation link; and a pair of elastic members having one ends connected to the left and right guide links and the other ends connected to the bottom panel, to apply elastic force to the left and right guide links.
According to another aspect of the present invention, there is provided a paper holding device for a label printer, comprising: left and right holders for supporting both ends, respectively, of a paper roll; left and right guide links respectively locked to lower ends of the left and right holders; a rotation link for operatively connecting the left and right guide links with each other and moving them in leftward and rightward directions; a bottom panel secured with respect to a floor of a printer body, for rotatably installing thereon the rotation link which functions to guide leftward and rightward movement of the left and right guide links; and an elastic member connected to the rotation link to apply elastic force to the rotation link as the rotation link is rotated.